Experimental Study of the Three Dimensionality of Orthogonal Blade-Vortex Interaction

Wind-tunneltestswereconductedtoinvestigateorthogonalvortexinteractionwith astationary blademimicking the main-rotor/tail-rotor interaction. High-quality experimental results with high-temporal resolution for the interaction have been obtained at different wind speeds and blade incidence angles. A vortex generator was specially designed for the experiment and produced stable trailing vortices. These were identie ed by hot-wire anemometry, with different vortical parameters for different speeds. When the measurement location is aligned with the vortex axis, pressure data reveal a suction peak on the upper blade surface and a pressure peak on the lower surface during the interaction. Signie cant dependence of the pressure on spanwise distance from the vortex indicates a strong three-dimensional interaction effect. For example, for spanwise positions above the core axis, a pressure pulse on the upper surface and a suction peak on the lower surface have been observed. It is shown that these differences can be attributed to the ine uence of the axial and tangential velocity components of the vortex. Pressure data for the blade at high incidence also show that the interaction can exacerbate and alleviate e ow separation, depending on the spanwise position.